Design An Intelligent RLC Testing Instrument Based On LM3S1138

Along with the vigorous development of the electronics industry, thedemand for accuracy electronic components increasing quickly. A highprecision, low cost, portable resistance capacitance inductance tester has vastapplied space. This article reference the traditional test instrument, combinedwith modern microprocessor application, designed the RLC tester to meet therequirements. In the selection of testing methods, this paper compares thealternating current bridge method, L-C resonance method and voltammetry,ultimately selected voltammetry for the design of RLC intelligent tester. Theinstrument has a signal generator, it can produce a series of adjustablefrequency AC waveform, though the oscillating circuit, Change the inductance L(or the capacitor C) into a frequency signal f, microcontroller LM3S1138sampling through the internal counter, calculate the pulse frequency thatproduced square wave, through a series of procedures operation ratio andsignal feedback regulation, the microcomputer adjust suitable range andnumerical value automatic, it can be also input though keybord directly. At lastmicrocontroller calculate the values of inductance or capacitance, send theresults through the serial port to the shift register, display in the LCD screen.At first, this article introduced the domestic and foreign instrumentationdevelopment, discussed the current situation of the domestic detectionapparatus and intelligent instrument development trend. Then introduces thecommonly measuring methods of resistance, inductance and capacitance,through the comparison of the issues, identified detection principle used in thisdesign.Emphasize the introduction to LM3S1138controller system’s internalstructure and function expansion. Take a detail Explain ahout signal generator’s signal generating circuit and a control circuit which used MAX038as the main chip. Focused on the system program flow and the practicalapplication, including frequency measurement, RLC measurement,man-machine communication and AD/DA module.Finally use the design ofcompleted tester for measuring the specific resistance, inductance andcapacitance values, recording the results and the errors of the correspondingprocessing, The results show that the design of the RLC tester achieves theexpected effect.